/**
 * author: redd
 * create_time: 2017/12/27 15:24
 * description:
 */
 

function main() {
  var canvas = document.getElementById('example')
  if(!canvas) {
    console.log('failed to retrieve the canvas element')
    return
  }

  var ctx = canvas.getContext('2d')
  ctx.fillStyle = 'rgba(0,0,255,1.0)'
  ctx.fillRect(120, 10, 150, 150)
}